It depends on the car. For example I couldnt even come close to building my malibu with whats in it for what I paid for it. Hell just the headders , exhaust , converter , trans , rear end , rear suspension and fuel system retail for what i paid for the car.
That of course is a race car where things are pretty cut and dry. We looked at the car and bought it because of this. Knowing if somthing happened most parts could be scavanged out and put in another body.

I think especially right now when the economy is shit having cash in hand can net you some killllleeerrrr deals.